Method and apparatus for separating materials



July 17, 1951 H. K. MARTIN 2,560,809

METHOD AND APPARATUS'FOR SEPARATING MATERIALS Filed July .10, 1946 3Shats-Sheet l ll'lllll INVENTOR. HENRY K Mam/1 M, Mew

July 17; 1951 H. K. MARTIN 2,560,809

METHOD AND APPARATUS FOR SEPARATING MATERIALS HENRY K Mnm'm BY W 1 1 H rTORNE v5 July 17, 1951 H. K. MARTIN 2,560,809

METHOD AND APPARATUS FOR SEPARATING MATERIALS Filed July 10. 1946 3Sheets-Sheet 5 I BY 1pm, Maxi fi y w flwzww.

Patented July 17, 1951 METHOD AND APPARATUS FOR SEPABATING MATERIALSHenry K. Martin, Ironwood, Mlch., assignor to Reserve Mining Company,Babbit, Minn., a corporation of Minnesota Application July 10, 1946,Serial No. 682,632

11 Claims. (Cl. 209-3) The present invention relates to theclassification or separation of mixed material of difierent specificgravity and/or of difierent particle size. More particularly, theinvention \relates to method and apparatus for classifying or separatingmixed material of different specific gravity and/or difierent particlesize by mixing the material to be separated with water in such a mannerthat the material of lesser specific gravity and/or smaller particlesize is washed away by the water while the material of greater specificgravity and/or larger particle size remains behind.

It is now well known that separation and washing of mixed insolublematerials of diflerent specific gravities may be eifected by introducingthe mixed materials into a body of flowing liquid so that the lighterparticles of the mixture are carried away from the liquid and theheavier particles settle. However, dimculty is encountered when theparticles of greater specific gravity are relatively fine since theywill not settle rapidly and hence are frequently carried away by theliquid along with the lighter particles. If the rate of flow of theliquid be reduced sufficiently to allow the said fine particles ofgreater specific gravity to settle, then the larger particles of lesserspecific gravity will also settle so that the separation eilected isvery unsatisfactory.

Therefore, one of the principal objects of the present invention is theprovision of a novel and. improved method and apparatus for classifyingor separating mixed material of different specific gravity and/orparticle size by washing the material with water in a manner to causethe material of lesser specific gravity and/or smaller particle size tobe carried away by the water 7 while the material of greater specificgravity and/ or larger particle size settles.

More specifically, it is an object of the invention to provide animproved method and apparatus for classifying or separating mixedmaterial of different specific gravity and/or particle size byintroducing the mixed material into a separating zone containinguprising currents of liquid whereby the particles of greater specificgravity will settle while the particles of lesser specific gravity willbe carried away by the liquid, the rate of settling being controlled bythe withdrawal of liquid from a point in the separating zoneintermediate the top and bottom thereof. The above mentioneddifficulties of separation are particularly prevalent when the materialto be separated is magnetic ore which is mixed with silica and othersubstances constituting what are known as gangue and middling materials.In order to free the magnetic ore from the undesired substances suchmaterial is customarily ground or pulverized to relatively smallparticle sizes with the result that the higher grade ore particles arefrequently of smaller size than the particles of the foreign substancesand the lower grade ore. Hence, when separation has been attempted byprior methods and apparatus employing a flowing liquid, the results areunsatisfactory since, in order to enable the fine particles of highergrade ore to settle, the rate of flow of the liquid has had to bereduced to the point where larger particles of unwanted substances oflesser specific gravity also settle.

Therefore, another object of the invention is the provision of a noveland improved method and apparatus of the character described forseparating ore concentrates from tailings and/or middling particles.

A further object of the invention is to provide an improved method andapparatus for separating magnetic ore concentrates from tailings and/ormiddling particles by applying a predetermined magnetizing force to themixed material and then introducing the material into a body of flowingliquid, whereby the magnetic particles will fiocculate or collect intosmall ag gregates and settle while the non-magnetic particles will becarried away by the fiowing liquid.

It is also an object of the invention to provide a novel and improvedmethod and apparatus of the character referred to which will be capableof continuous operation, emcient, and yet simple and inexpensive tooperate.

The invention further resides in certain steps of procedure andconstructions, combinations and arrangement of apparatus; and furtherobjects and advantages thereof will be apparent to those skilled in theart (to which the invention relates) from the following detaileddescription of the preferred embodiments thereof and from the appendedclaims.

Before entering upon a detailed description of the preferred embodimentof the apparatus, it is believed the invention can be better understoodby first disclosing the improved procedure for efiecting separation ofinsoluble material existing as a mixture of particles having differentspecific gravities and/ or particle sizes.

In accordance with this procedure such a mix ture is fed into the top ofa separating zone conthining water or other liquid in a manner tosubstantially uniformly distribute the mixed material throughout theupper portion of the separating zone without producing turbulence in theliquid contained therein. At the same time liquid is introduced into theseparating zone below the point of introduction of the mixture, undersufficient head and so directed as to produce substantially uniform,non-turbulent upward currents within the separating zone. These currentsencounter the particles of the mixture to wash and separate them.Simultaneously, liquid is withdrawn from the zone from a regionintermediate the top and bottom of the zone and below the point ofintroduction of the liquid therein. This withdrawal of liquid is at arate so correlated with the rate of introduction of the liquid and ofthe mixture as to produce an overfiow of the liquid at the top of thezone suflicient to carry ofi therewith the particles of the mixturehaving specific gravities and/or particle sizes less than apredetermined value. The particles of greater specific gravity and/orparticle size therefore settle to the bottom of the separating zone fromwhich they are removed.

When the material to be separated is magnetic ore concentrates which aremixed with tailings and/or lower grade ore, the procedure furtherincludes the step of subjecting the mixture to a 25 predeterminedmagnetizing force prior to the introduction of the material into theseparating zone. This magnetizes the particles of high grade ore so thatthey will fiocculate or gather into small masses within the separatingzone and hence facilitate the settling thereof. The lower grade orand/or tailings will either not be magnetized,

or only slightly magnetized, so, that this material will not fiocculateand hence will act as in-. dividual particles which, being relativelysmall 4 4 and collects at the bottom of the tank. The lower end of themember l3 may be connected to a pipe or other suitable means forcarrying oil? the material discharged therethrough, the rate ofdischarge being regulated by a valve [3a, pump or other suitable means.The tank A may be supported in any suitable manner. As shown, the bottomI0 is slightly recessed with respect to the lower edge of the sidewallsII and the lower circumference of the tank has an angle iron I4 roundingthe upper edge of the tank proper and extending above and below the topthereof forms the outer wall of the discharge chamber l5, the bottombeing formed by a helically arranged member ll interposed between thetank proper and the member I. The construction is such that material. inthe discharge chamber I5 is caused to flow toward an outlet l8 at oneside of the apparatus. The upper edge of the tank proper is formed by anannular member or ring I9 conandlight, will be carried upwardly by therising V currents of liquid and pass out of the separating zone in theoverflow therefrom. I

While the steps of this procedure may be carried out by a variety ofdifferent devices the in vention also includes an apparatii's'which isoperable to perform the method; .the present preferred embodiment of theapparatus being described with reference to the accompanying drawingsforming a part of this specification in which similar referencecharacters designate corresponding parts. and in which:

Fig. 1 is a side elevational view of an apparatus embodying the presentinvention with the outlet valve at the bottom omitted;

Fig. 2 is a sectional view, with portions in elevation, approximatelyone the line 2-2 of Figs. 1 and. 4 and showing the outlet valve at thebottomiof the apparatus;

Fig. 3 is a fragmentary sectional view of the upper part of theapparatus, approximately on the line 2-2 of Fig. l but showing the partsin a different operating position;

Fig. 4 is a sectional view, with portions in plan, approximately on theline 4-4 of Fig. 2;

Fig. 5 is a fragmentary sectional view, approximately on the line 55 ofFig. 2 with certain elements partially broken away; and

Fig. 6 isa fragmentary sectional view of the central portion of theapparatus taken approximately at right angles to the line 2-2 of Fig. 4.

Referring to the drawings, the reference character A- designatesgenerally a vessel or tank having a funnel-shaped bottom I0 andvertical, cy-

lindrical, side walls I l. The bottom I0 is provided with a centralopening 12 communicating with the upper end of a funnel-shaped memberl3, the lower end of which constitutes the discharge outlet or openingfor the material of greater specific gravity or larger particle sizewhichsettles ly with respect thereto so that the top'of the tank can beleveled thereby assuring a uniform flow of liquid and material from thetank to the discharge chamber l5 around the entire periphery of thetank. As shown, the member or ring I! is bolted to the side walls II bybolts 20 which project through elongated slots 2| in the ring IS. Thetank, including the discharge chamber 15,

is provided with a cover-22 supported by/and secured to-thc-ifipei' edgeof the annular inember IS. The cover 22 may be of any desiredconstruction. In the embodiment shown, certain apparatus, hereinafterreferred to, is mounted on or supported by the cover which is providedwith a wood flooring 23 vto facilitate walking thereon, etc.

Material to be treated or separated, mixed with water or other suitableliquid, is supplied to the 22 and flooring 23 through which a verticallypositioned, cylindrical member 28 extends with its upper end in contactwith, or closely adjacent to, the lower side of the pipe 24. Thiscylindrical member 28 is welded or otherwise secured to the cover 22 andconstitutes the outer wall of an annular chamber 21 into which thematerial supplied by the pipe 24 is discharged. Equal distribution ofthe material within the chamber 21 may be efiected by any conventionalmeans; for

example, by the use of a plurality of spaced feeding conduits 24 or bymeans of a mechanical distributor, not shown. However, since thematerial generally contains considerable liquid, its

angle of repose will be substantially zero andhence a single pipe orconduit 24 will ordinarily wall of which is-formed by a cylindricalmember II. The cylindrical members 30, 3| are coaxially arranged withrespect to each other andto the cylindrical member 28 and are fixedlysupported therein, as will be hereinafter apparent. The lower end of thecylindrical member 28 extends below the top of the tank proper and thebottom of the chamber 21 is formed by a perforated annular plate 32interposed between and welded to the cylindrical members 28 and 30.

A cylindrical member 29, having a diameter larger than the diameter ofmember 28, is positioned within tank A coaxially with the members 28, 30and 3|, and so disposed that the lower end of the member 28 extends ashort distance below the upper edge of the member 29. Perforated annularplates or members 35 extend between the tubular members 29 and 35 andare welded or otherwise secured thereto. As will be seen in Fig. 2, theperforated members 35 are spaced vertically below and parallel with theperforated plate 32 so that a chamber 33 is formed by the members 29, 39and 35 and this latter chamber is below the aforementioned chamber 2?.

Depending from and welded to the lower surface of the cover 22 is acylindrical member 34 which has a diameter greater than the diameter ofthe cylindrical member 29. The members 29 and 3d are coaxially disposedand the length of the latter is sufficient to extend below and surroundthe upper portion of the former. There is thus provided a tortuous pathfor the material to be separated. As indicated by the arrows in Fig. 2,the material discharged from the conduit 2t enters chamber 21, flowsthrough the holes in plate 32 into chamber 33 where water or otherliquid flowing upwardly through the holes in plates 35 (as hereinafterdescribed) carries the material to and through the spaces between thecylindricalmembers 28, 29 and 33 and into the main body of the vessel ortank A.

In addition to the liquid or water supplied to the tank A, along withthe material to be separated through the feed pipe 2t, additional liquidor water, hereinafter referred to as Wash water, is supplied underpressure to the tank by a conduit or pipe 38, the right-hand end ofwhich (as viewed in Fig. 2) projects through an aperture in thecylindrical member 30 and communicates with the upper end of a chamberor well ti intermediate the tubular members 30, 3!. The upper end of thewell 41 is closed by a platelike member 42 and the lower end thereof bya plate-like member 43. The plate-like member ft is interposed betweenthe inner and outer cylindrical members 3H, 35 and is welded thereto.The plate 42 is welded to the upper ends ofthe cylindrical' members 30,3! and extends outwardly therebeyond to provide a support for a gearhousing subsequently to be described. Suitable angle members 6| may bewelded between the lower side of plate 42 and the outer surface ofcylindrical member 30 to reinforce the overhanging portion of the plate2.

The lower portion of the cylindrical member 30 is provided with aplurality of apertures 44 which establish communication between theinterior of member 38 and a chamber 45, formed by the lower ends ofcylindrical members 29, 3d and the perforated plates 35. The lower endof the cylindrical member 29 or, more specifically the chamber 35communicates with the interior of a relatively fiat, cone-like, hollowmember or washpan, designated generally by the reference character B.The upper side of the washpan B is formed by a plurality of perforatedplates 46 which have their adjacent edges secured together and theirinner ends welded to the lower edge of the cylindrical member 29. Thelower side of the washpan B is formed by a plurality of plates 41 whichhave their adjacent edges secured together and their inner ends weldedto the lower end of the cylindrical member 30. The outer ends of theplates 46, 41 are connected by plates or members 48 welded thereto whichclose the outer ends of the space 49 between the vertically spacedplates 46, 41.

Wash water entering through pipe 38 flows downwardly through the well 4|and enters chamber 45 through the apertures 44 in the lower end ofcylindrical member 30. Part of this wash water, entering the chamber 45,flows through the perforations in the plates 35 into the chamber or feedwell 33 where it mixes with the water and material entering through theperforations in the plate 32. The rest of the wash water entering thechamber 45, flows into the space 49 in the washpan B and enters the tankproper through the perforations in the members 46. The material ofgreater specific gravity or the particles of larger size entering thetank A through the tortuous path previously described, fall towards thetop of the inverted, cone-like member or washpan B Where they are washedby the water entering the tank A through the perforations in the plates46 as the said particles move toward the lower outer edge of thewashpan. The lighter or smaller particles are carried upwardly withinthe upper portion of the main body of the vessel or tank A by theuprising currents of water flowing through the perforations in theplates 46. The number and spacing of these perforations are such thatthese uprising currents are substantially uniformly distributedthroughout the cross sectional area of tank A above the washpan B.

The material to be separated is, therefore, agitated and washed in thefeed well 33 by the water entering the same through the perforations inthe plates 35 and again in the tank by the water entering the tankproper through the perforations in. the plates 36. This separates thematerial of greater specific gravity or of larger particle size fromthat of lesser specific gravity or smaller particle size and causes thematerial of lesser specific gravity or of smaller particle size to befloated or washed out of the tank proper by the portion of the waterwhich flows over the edge of plate l9 and into the discharge chamber I5.The material of greater specific gravity or of larger particle sizeenters the lower part of the tank through the space or slot between theperiphery of the washpan B and the side walls ll. As the material ofgreater specific gravity or of larger particle size collects in thebottom of the tank, it is withdrawn therefrom through the dischargeopening l2 in the bottom of the tank.

In the embodiment shown, the material which collects at the bottom ofthe tank is scraped toward the opening l2 by a spiral rake comprising apair of blades 50, 5i connected to radially extending arms 52, 53operatively connected to a vertically extending shaft 53 locatedcentrally of the tank A. The inner ends of the arms 52, 53 are connectedto a collar member 55 fixed to the shaft 53. This rake structure isstrengthened by braces 55. 5! connected between the arms 52, 53 and amember 53 fixed to the shaft 53 above the collar 55. The shaft 563 isadapted to be rotated d/or raised and lowered in a manner here terspecifically described.

To further assist the discharge of material through the opening II, aplurality of arms 59 are connected to the lower sides of the arms 52,53. These arms 59 extend below the blades 5i and are shaped to fitwithin the opening I! and the inner surface of funnel member l3 inspaced relationship thereto. The arms 59 are strengthened and held fromdeflection by bands or rings 53a. The rate of discharge may becontrolled by the amount of opening of valve l3a.

The shaft 54 extends upwardly through the center of the member B andthrough a housing 50 resting upon and fixed to the plate 42 which issecured to and closes the top of the cylinder members 30 and 3i. Thebottom member 62 of the housing 30 includes an upwardly projecting,cylindrical boss 63 through which the shaft 54 projects and which bossforms a guide means for the upper part of the shaft. A part of the shaft54 adjacent to the boss 63 is splined and the shaft above the splinedsection is of reduced diameter and threaded. The splined section of theshaft 54 has a worm wheel 64 splined thereto, which worm wheel iscontinuously in mesh with a worm 65 rotatably supported in the housing53 and connected to an electric motor 66 through a variable speed changetransmission 61, and a sprocket chain drive 68, all of which are ofcommercial design. The construction is such that the shaft 54 can bedriven at any desired speed. I

The reduced threaded part of the shaft 54 above the splined section justreferred to is provided with a nut 10, including a hand wheel II, forfacilitating adjustment thereof.. The shaft 54 is supported by ananti-friction thrust bearing I2 interposed between the lower surface ofthe nut and anupwardly extending boss 13 on the dome-shaped cover 14 ofthe housing 50. The cover 14 has a downwardly extending boss 15 formedintegral therewith, which boss together with the boss 63, previouslyreferred to, limits the vertical movement of the worm wheel 84 and formsa guide for the upper end of the shaft 54. A jam nut Illa is provided onthe threaded portion of the shaft 54 to lock nut 10 in any adjustedposition. The construction is such that manipulation of hand wheel Iiraises or lowers the blades 50 and 5| thus enabling them to be adjustedrelative to the bottom in of the tank or vessel A to regulate theiraction upon the material which settles to the bottom of the tank. Fig. 2shows the blades in their lowermost position,while Fig. 3 illustratesthe position of the handwheel II and shaft 54 corresponding to theuppermost position of the blades.

Thus far the apparatus has been described as though the upper part ofthe tank proper and the chambers 33, 45 and 49 were annular in shape andpermitted free circulation of the liquid in a horizontal plane, butpreferably 'the upper part of the tank proper and the chambers 33, 45and 49 are divided into comparatively small compartments C, D, E and Fby vertically positioned, radial partitions or webs 15, 11, I8 and I9,respectively. In the present embodiment, which is constructed ofwelded-up steel plates, the webs 16, ll, 18 and 19 in any one verticalplane are formed by a single plate which extends from the bottom of thewashpan B to the cover 22 and from the outside walls I l to thecylindrical member 30, excepting the chamber 21 within member 28. andthat small part'of the feed well 33 loformed by separate web members.

8 cated above the lower end of the cylindrical mem ber 23.

As shown, (see Figs. 2, 4 and 5) the lower end of the cylindrical member29 is slotted to allow the web plates to pass therethrough; the top ofthe washpan B is made up of a plurality of plates 48 welded to andseparated by the web plates; and the bottom of the feed chamber 33 ismade up of a plurality of plates 35 with the web plates extendingtherebetween. Alternatively, the top of the washpan and/or the bottom ofthe feed well 33 could each be formed of a single plate and the variouscompartments in the respective chambers The web construction not onlypermits a better controlled flow of liquid and material through theapparatus (by preventing swirling) but also provides a strong rigidconstruction. The lower end of each compartment D. is provided with oneor more holes through which material that may collect therein canescape.

To provide a more thorough washing of the material and further preventswirling of the material and liquid, each compartment C has a pluralityof inclined perforated bailie plates 3| extending thereacross andsecured to the adjacent vertical battle plates 15. Preferably the topedges of the baflles 8| are located a substantial distance below the topof the overflow plate I9 and the bottom edges of the baiiles iii arespaced from the plates 46 forming the top of the washpan B. Theinclination of the baiiies 8| is towards the central portion of the tankA thus tending t direct the water rising from the washpan towards thematerial entering from chamber 33.

As previously mentioned, the material of greater specific gravity, orthe particles of larger size, settle downwardly in the tank or vessel Apassing through the slot or space between the outer walls ll of the tankand the outer edge of the washpan B. The rate of this settling must beaccurately controlled for if the rate is too fast the" material oflesser specific gravity and smaller particles size, which should passout the overflow, will also settle. Conversely, if the rate of settlingis too slow, some of the heavier and large particles will be carriedinto the overflow. The rate of settling may be controlled by regulatingthe rate of feeding of material through pipe 24, by regulating the rateof supply of water to the washpan B, by the amount of opening of valveI3a, and by the width of the space or slot between the outer edge of thewashpan B and the walls ll of the vessel A. However, for a giveninstallation, the last of these factors (i. e.. the width of the slot)is fixed. Moreover, the rate of supply of wash water must be kept withina certain range to provide adequate washing. Likewise, for efilcientoperation the rate of supply of material to the a paratus cannot be tooslow. Finally, if the valve l3a be opened too wide, an undue amount ofwater will be discharged with the settled material which is undesirable.Conversely, if valve i 3a be closed too far, the removal of separated 9plate 43 which is disposed within the central portion of the washpan aspreviously described. The pipe 82 slopes downwardly to a point adjacentthe side Wall ll of the tank A where a coupling 85 unites it to a pipe86 extending through the wall I I. The coupling 85 may be flexible, ifdesired, to enable the pipe 82 to be easily installed and its angle ofinclination adjusted. A valve 81 is provided on the end of pipe 86exteriorly of the sidewall I I to provide a means for controlling therate of withdrawal of liquid from the tank. Obviously, a pump or othermeans to control the flow of liquid from the tank could be substitutedfor the valve 81, if desired.

The liquid within the tank A will rise up under washpan B and into theinterior of cylindrical member 3| to the same level as the liquidoverflowing ring l9 since the interior of the tubular member 3| isvented to the atmosphere by a means of pipe 88 passing through thecylindrical members 30 and 3|. This liquid under the washpan and withinthe cylindrical member 3| will be substantially clear and free fromsolids s that it may be removed without loss of the material which hassettled to the bottom of the tank. The rate of withdrawal of this clearliquid is regulated by the amount of opening of the valve 81. Since theliquid so removed can only be replaced by the liquid which is suppliedto the portion of the tank above the washp-an and passes downwardlythrough the annular space between the edge of the washpan and the sidewall I i of the tank, the

amount of opening of valve 81 provides an accurate means to control therate of settling of material without disturbing the optimum rate ofsupply of material, wash water, and the desired opening of the dischargevalve I311.

The apparatus described thus far will operate satisfactorily to separatemany types of material; asfor example, sand from clay and othersubstances. However, when the material to be separated contains magneticiron ore in the form of relatively small particles, it has been foundthat separation is facilitated if the material be subjected to apredetermined magnetizing force prior to introduction into the vessel ortank A. For example, Eastern Mesabi magnetic taconite, after apreliminary treatment including grinding, contains fine particles whichare ordinarily of higher grade ore, the coarser particles generallybeing lower grade because of comparatively large attached particles ofsilica or silicate. It has been found that if such material bemagnetized after grinding and then demagnetized, the magnetic particlesattached to particles of silica are more easily demagnetized than thefine unattached particles. Hence, under proper magnetizing and/ordemagnetizing prior to introduction into the vessel A, the fineparticles (high grade ore) will have suificient magnetism to collectinto comparativel large masses in the vessel and settle "to the lowerdischarge opening while the less strongly magnetized, coarse middlingparticles will not so collect and hence will be carried into theoverflow.

The desired magnetization of the material prior to introduction intovessel A may be effected by associating suitable demagnetizing andmagnetizing means with the material supply conduit M to act upon thematerial as it passes therethrough. For example, a magnetizing coil orsolenoid 89 and a demagnetizing coil or solenoid as are schematicallyrepresented in Fig. 2 as disposed about the conduit 25 and supplied withD. C. and A. C. current, respectively, which may be varied byconventional means not shown. These solenoids may be of any desiredconstruction and the order in which they are arranged is immaterialsince the strength of the field produced by the respective coils orsolenoids can be varied to give the best results on any given ore.

Whether one, both or none of the Coils 89 and 90 be used, and thestrength of the field produced thereby, is dependent upon the nature ofthe material to be separated and its prior treatment. Thus, if the priortreatment of the material has included a preliminary separation by meansof a conventional magnetic separator (such as that known as a Dingsseparator), the material may be sufliciently magnetized so that neithercoil need be employed. If the material be magnetized, but the extent ofmagnetization be not known, it is frequently desirable to demagnetize itby means of coil 90 and emagnetize-it by means of coil 89 so as toproduce the desired amount of magnetization. Finally, if the materialwas not previously magnetized, or magnetized to a lesser extent thandesired, only coil 89 need be employed. In all cases, however, theresulting magnetization of the material should be sufficient to enablethe fine particles of higher grade ore to flocculate, or collecttogether into smal1 masses, but not so great as to interfere with theseparation (as by enabling the higher grade ore particles to cling tothe gangue or middling material, or to mechanically hold such undesiredsubstances in masses of the flocculated higher grade particles).

It is believed that the steps of the method and the operation of thedevice will be apparent from the foregoing description thereof. Sufiiceit to say that material to be separated is introduced through the feedpipe 2 8 and, if the material includes magnetic ore, may be subjectedtherein to a controlled magnetic force (by solenoids 89 and/or 90). Fromthe discharge end of pipe 24 the material enters the feed chamber 2'5and passes therefrom through the perforated plate 32 into the chamber33, the plate 32 assisting in uniformly distributing the material withinthe chamber 33. The material is further distributed within chamber 33and is washed by water admitted under pressure through the pipe 38 andperforated plates 35. The extent to which the material is washed at thispoint can be controlled by varying the amount and/or pressure of thewash water admitted through the pipe 38 in relation to the amount ofmaterial introduced through the feed pipe 24.

The material and washing water then flow over the upper edge of thecylindrical member 29, and through the space between the latter andcylindrical member 35, into the upper portion of main body of the tankA. Here the material is further washed and separated by the currents ofwater rising through the opening in the top of the washpan B. Theparticles of greater specific gravity and/or particle size settle to thebottom of the tank through the slot between the washpan and the sidewalls of tank A. When the material being separated is finely groundmagnetic iron ore, the settling of the iron ore concentrates isfacilitated by the flocculation thereof due to the prior magnetizationof the particles. The tailings or material of lesser specific gravity,or of small particle size, rise and overflow the sides of the tankproper and are carried away by the discharge chamber i5. The settledmaterial in the lower portion of tank A is raked to the center of thetank and discharged through the opening l2, the

' amount of opening of the valve Ila controlling the dilution of thematerial leaving the tank. In addition to washing the material beingconcentrated, the water added through the washpan assists in controllingthe velocity or flow through the tank, a further and-finer control beingexercised by the rate of withdrawal of water through pipe '2. The smallarrows in Fig. 2 suggest the direction of flow through the apparatus.

From the foregoing, it 'will be apparent that the objects of theinvention heretofore enumerated have been accomplished and that a noveland improved method and apparatus have been provided for separating orclassifying material of difierent specific gravity and/or differentparticle size. While the preferred embodiment of the apparatus of theinvention has been described in considerable detail, the invention isnot limited to the particular construction shown, which may be varied.Also, while the method of this invention may be performed by theapparatus described above, it is not limited thereto since theprocedural steps may be effected by other and different devices andcertain of the steps may be varied or omitted. Therefore, I do notregard my invention as confined to the exact procedural steps andstructural details disclosed, but it is my intention to cover hereby alladaptations, modifications and uses thereof which come within thepractice of those skilled in the art to which the invention relates andwithin the scope of the appended claims.

Having thus described my invention, I claim:

1. A method of separating magnetic particles from a mixture containingmagnetic particles non-magnetic particles, and particles of magneticmaterial united with non-magnetic material, comprising applying ademagnetizing force to the mixture, applying a magnetizing force to thedemagnetized mixture to produce a predetermined magnetizationof themagnetic particles and a lesser magnetization of the particles ofmagnetic material united with non-magnetic material, introducing themagnetized mixture into the upper portion of a separating zonecontaining flowing liquid, controlling the flow of the liquid in theseparating zone so that the rate thereof is suilicient to preventflocculation of the particles which contain magnetic material unitedwith non-magnetic material while permitting the magnetic particles tocollect together and settle to the bottom of the zone under theinfluence of gravity, the rate of flow of the liquid being sufiicient tocause some of the liquid to flow out of the top of the zone and carrytherewith the nonmagnetic particles and the particles of magneticmaterial united with non-magnetic material, and removing the magneticparticles from the lower end of the said zone.

2. A method of separating magnetic particles from a mixture containingmagnetic particles non-magnetic particles, and particles of magneticmaterial united with non-magnetic material, comprising applying ade'magnetizing force to the magnetized mixture to partially demagnetizethe mixture whereby a predetermined magnetization of the magneticparticles and a lesser magnetization of the particles of magneticmaterial united with non-magnetic material is produced, introducing themixture into the upper portion of a separating zone containing flowingliquid, controlling the flow of the liquid in the separating zone sothat the rate thereof is sufflcient to prevent flocculation of the lessstrongly magnetized particles while permitting the more gravlties,respectively, greater than and less than a predetermined value, whichcomprises providing a separating zone containing liquid, introducing themixture into the liquid in the upper portion of the zone withoutturbulence, introducing liquid into said zone from a region below thepoint of introduction of the mixture in a manner to produce asubstantially uniform, nonturbulent upward current within the said zone,withdrawing liquid which is substantially free of said insolublematerial from a point substantially centrally of said zone intermediatethe top and bottom of the zone beneath the upward current of liquid insaid zone, the'rate of withdrawal of the liquid being so related to therate of introduction of liquid as to result in an overflow of liquid atthe top of the zone sufllcient to carry therewith the material of themixture having specific gravities less than said predetermined valuewhile permitting the material having specific gravities greater thansaid predetermined value to settle to the lower portion of the zone, andwithdrawing the settled material from the lower portion of the zone.

4. In apparatus of the character referred to. a vessel having anoverflow opening adjacent to the top and an outlet adjacent to thebottom. means for controlling flow through said outlet, a hollowmember-within said vessel extending adjacent to but spaced from the sidewalls of the said vessel, the said member having an inclined uppersurface provided with a plurality of openings communicating with theinterior of the member, means for conducting liquid under pressure intothe interior of said member, means for supplying material to beseparated to said vessel above said inclined'upper surface, meansadjacent to the bottom of said vessel for stirring the portion of thematerial which descends thereto for directing the said material to theoutlet, and means having an inlet positioned substantially centrally ofsaid vessel below said hollow member and above the outlet of the vesselfor withdrawing liquid from the vessel at a controlled rate to therebyregulate the rate of descent of the material in said vessel.

5. In apparatus of the character referred to, a generally cylindricalvessel having an overflow opening adjacent to the top and an outlet inthe center of the bottom, means for controlling flow through saidoutlet, a generally cone-shaped hollow member within said vesselextending adjacent to but spaced from the vessel walls, the uppersurface of said hollow member having a plurality of openingscommunicating with the interior of the member, means for conductingliquid into the interior of said member, means for supplying material tobe separated to said vessel above said surface and adjacent to thecentral portion thereof, and means having an inlet positionedsubstantially centrally of said vessel above the outlet of the vesseland adjacent the lower side of said hollow member in a position wherethe inlet to the last-mentioned means is shielded by said hollow memberfrom material settling in said vessel so that the said last-mentionedmeans is effective for withdrawing liquid which is substantially free ofmaterial particles from the vessel at a controlled rate to therebyregulate the rate of descent of the material i said vessel.

6. In apparatus of the character referred to, a generally cylindricalvessel having an overflow opening adjacent to the top and an outlet inthe center of the bottom, valve means for said outlet, a generallycone-shaped hollow member within said vessel extending adjacent to butspaced from the side walls of the vessel, the upper surface of saidmember having a plurality of openings communicating with the interior ofsaid member, means for conducting liquid into the interior of saidmember, means for supplying material to be separated to said vesselabove said upper surface and adjacent to the central portion thereof, aconduit for withdrawing liquid from said vessel, the said conduit havingits inner end open and located substantially centrally of said vesselabove the outlet of the vessel and adjacent the lower side of saidhollow member in a position where the said inner end of the conduit isshielded by said hollow member from material settling in said vessel sothat the said conduit is effective for withdrawing liquid which issubstantially free of material particles, and means for controlling thewithdrawal of liquid through the conduit to thereby regulate the rate ofdescent of the material in said vessel.

7. In apparatus of the character referred to, a generally cylindricalvessel having an overflow opening adjacent to the top and an outlet inthe center of the bottom, valve means for said outlet, a generallycone-shaped hollow member within said vessel extending adjacent to butspaced from the side walls of the vessel, the upper surface of saidmember having a plurality of openings communicating with the interior ofsaid member, vertically positioned radial baffles in said vessel abovesaid member, means for conducting liquid into the interior of saidmember, means for supplying material to be separated to said vesselabove said upper surface and adjacent to the central portion thereof,and means having an inlet positioned substantially centrally of saidvessel above the outlet of the vessel and adjacent the lower side ofsaid hollow member in a position where the inlet to the last-mentionedmeans is shielded by said hollow member from material settling in saidvessel so that the said last-mentioned means is effective forwithdrawing liquid which is substantially free of material particlesfrom the vessel at a controlled rate to thereby regulatethe rate ofdescent of the material in said vessel.

8. In apparatus of the character referred to, a generally cylindricalvessel having an overflow opening adjacent to the top and afunnel-shaped bottom having an outlet'in the center, valve means forsaid outlet, a hollow member within said vessel having a substantiallycircular side wall concentric with but spaced from the side wall of thevessel, said member having an upper surface including a portion slopingsubstantially uniformly downwardly toward the side wall of the vesseland provided with a plurality of openings communicating with theinterior of said member, means for conducting pressure liquid into theinterior of said member, means for supplying material to be separated tosaid vessel above said surface and adjacent to the central part thereof,a plurality of vertically extending radial ,baflies in said vessel abovesaid hollow member, a plurality of spaced inclined bailles extendingbetween adjacent ones of said radial baflles, and means below saidhollow member and above the outlet of the vessel for Withdrawing liquidfrom the vesselat a controlled rate.

9. In an apparatus of the character referred to for separating materialcontaining magnetic particles non-magnetic particles and particles ofmagnetic material united with non-magnetic material, a vessel having anoverflow opening adjacent to the top and a restricted outlet adjacent tothe bottom, a hollow member within said vessel, said hollow memberhaving an upper surface extending generally transverse of said vesseland adjacent to but spaced from the side walls of the vessel, the saidupper surface of said'hollow member being provided with a plurality ofopenings communicating with the interior of the member, means forsupplying liquid to the interior of said hollow member under sufficienthead to flow through the said openings and produce uprising currents inthe portion of the vessel above the said hollow member, means forsupplying a material to beseparated to said vessel abovethe uppersurface of said hollow member, means for regulating the magnetization ofthe material as it is introduced into said vessel in a manner such thatthe magnetic particles in said material have sufficient magnetism toflocculate and settle through the liquid in said vessel to the bottomthereof and the particles having magnetic material united withnon-magnetic material have insufficient magnetism to fiocculate and arecarried with the non-magnetic particles to and through the overflowopening by the rising currents of liquid, means having an inletpositioned substantially centrally of said vessel above the said outletand adjacent the lower side of the said hollow member in a positionwhere the inlet to the last -mentioned means is shielded by said hollowmember from material settling in said vessel so that the last-mentionedmeans is effective for withdrawing liquid which rial, the steps ofregulating the magnetization of the mixed material so that the magneticparticles are more strongly magnetized than the particles containingnon-magnetic material united with magnetic material and then introducingthe mixed material into the upper portion of a separating zonecontaining an upwardly flowing liquid while removing liquid which issubstantially free of material particles from said zone in a regionintermediate the top and bottom of the zone beneath the point ofintroduction of the material and liquid into the zone and above theoutlet of material from the zone, the magnetization of the material andthe rate of flow of said liquid being so regulated that the magneticparticles flocculate and descend to the bottom of the zone while theparticles containing non-magnetic 15 material united with magneticmaterial do not flocculate and are carried together with the nonmagneticparticles to the upper portion of the- The following references are ofrecord in the file of this patent:

16 UNITED STATES PATENTS Number Name Date Bent Apr. 5. 1910 Darrow Aug.11, 1914 Noriega May 29, 1923 Elder Apr. 15, 1924 Andrews Mar. 12, 1929Daman Apr. 3, 1934 I Wuensch Apr. 10, 1945

